All the old forum posts
Originally posted by gotwind
Heres how to post images on this forum.
The Futures Green - Getwind of it.
Still dont know how to get pix on here. However, heres the latest conversation with Del - I hope he doesnt mind me cutting&pasting:
Hi Del, yes the champagne had a heck of a hammering after that!
Answers to your questions are in blue below.
Nice one Tim,
I recognise the genny as from renewablecomponents from ebay. £180ish? They did sell a few on their previous evolution models that had a lot of cogging effect but sold them very cheap. A few of the guys from www.gotwind.org bought them but werent able to modify them well enough to use.
Yep, youve got it, thats one of the cheap old ones there, I grabbed it for £47. It does indeed take quite a bit to start up, at the moment Im running it on a 9ft dia 3 blade wooden prop. Though Im seriously considering going for one of RenewableComponents own 6-bladed 6ft props instead (not on eBay but available direct from their own website), after watching a Danish wind turbine on UTube. It overspeeded and actually exploded. Im not too comfortable with my own wooden effort after seeing that, the blades would make fine javelins at a few hundred RPM. Even though each one is secured to that 5mm aluminium disk by 5 x M10 high tensile steel bolts, the wood itself could fracture. Im hoping that the torque would be similar or higher from a professional 6 blader as opposed to my badly-carved and unaerodynamic 3 blader, and that the smaller dia would also let it turn a bit faster than my present prop.
Its currently working quite well for something only a few feet up in the air (planning restrictions) and close to the house in a lot of turbulence. The turbulence is why I currently have it pointed in a fixed direction, when I move house (sometime in the next couple of years, probably), one of the considerations will be somewhere with smoother air and with higher than my current locations average 4.5 m/s, and then Ill stick a swivel mount and a tail on it.
Are you running it at 12v? I thought they were either 24v or 48v units?
Yes, only 12V at the moment, the dia of the prop needed to get it going means that it doesnt spin fast enough to hit 24V very often so I came down to 12 for starters. Seems to work, but Id much rather work with high voltage/low current than the other way around. You know the old saying: "Volts Jolt, But Amps Cramp." I really, really dont like high currents. Perhaps I will reconfigure the head unit to include voltage doubling.
How come your own flux axiel design never worked sufficiently? Seems a shame after all the work you put in.
To be honest I got hacked off with it, the redesign to pull the magnetic flux through the stator coils from the single magnet rotor introduced a horrific amount of cogging, so its sitting in the loft at the moment. But if when I move, the new place has a stream that I can waterwheel, Ill have torque to spare.....
Do you need shotty diodes when youre rectifying the output. I thought the bridge rectifier would take care of that?
True. At the moment the turbine head unit does the rectifying with 3 x 35A bridge rectifiers. Im half expecting them to blow up and will probably replace when they do with one of RS Components nifty 3-phase 86A bridges (RS 193-133). The 3 Schottkys in the picture are the barrier to stop the juice coming back out again, each is only 30A so I have stuffed 3 in parallel to run at 90A or thereabouts. Luckily their forward drops are fairly well matched to each other.
Like the look of your charge controller. What have you got insidfe the box that will handle 1KW and what dump load are you using?
<embarrassed grin> er....its a standard Beewind 50A unit. Yes, I know, I know. In due course and when I can be assed (probably when its blown up!) Ill whip up a simple little pulse width modulator controller, probably using an LM324 chip, and drive a few power MOSFETs (like RS 193-464) to do the actual power switching. In the meantime Ive arc-suppressed the relay contacts with a 100R resistor and a 0.47UF X2-type capacitor in series across them. Driving the sensor from just one of the batteries means that it will still work on an overall 24V system (if I reconfigure to 24V).
Dumps are interim and utterly simple. Theyre just a few cheap 3KW convector radiators from B&Q in parallel, about £14 each. At 24V each one should eat about 300W. OK, the resistivity might not be linear with voltage, but it should be more or less close enough. In my new place (dreaming again) Ill probably stick a couple of 24V 600W immersion elements into a secondary hot water cylinder. If I get an indirect type cylinder Ill be able to supplement the wind with some thermosyphoning solar panels I could knock up out of old black-painted radiators thrown in insulated glass-fronted boxes.
Whats your thinking of having separate boxes for incoming power and charge control? Surely the voltmeter will just default to the battery voltage level when all connected up but as you say its showing high and 16v?
Im using the LCD meter in the charge controller box (meter from DPMeters) as a battery monitor rather than measuring the raw input to the system as a whole. The analogue meters in the incoming box do that, and I always think that while you cant beat digital for accuracy, theres just something more gutsy about bouncing needles. Its showing high because the measurement point comes before all the electronics voltage drops further down the line - I think. Or I calibrated it wrong!
Ive recently bought a Futurenergy PMG. I managed to strike a deal with the supplier that meant we could get them for £105 + VAT plus P&P if we bought 5 and so I managed to get a few guys from the gotwind forum to buy some with me. Not sure it itll ever get used where I live (too big really) but i will hopefully be emigrating to France later this year so I will be used there big time.
Best wishes for France. I understand theyre a lot more progressive about domestic wind generation planning regs than this bloody country!
Do you fancy joining the Gotwind forum now and showing all your very neat work?
I might just do that. Nothing ventured, nothing gained, and having lurked on various sites it might be time to put something back.
PS: Neat???? You havent seen inside the boxes...........
Users browsing this forum: Yahoo [Bot] and 6 guests